$15\mathrm{.}8$ A needle is used to inject a given volume of a drug into a patient in a certain amount of time $\backslash ($ t$\_\{0\}\backslash ).$

What effect will the following have on the amount of time it takes to inject a fixed volume of this drug?

$($you can assume that all aspects not addressed remain the same$)$

$($a$)$ Reducing the length of the needle to $\backslash (60\backslash \%\backslash )$ of its original length.

$($b$)$ Increasing the length of the needle to $\backslash (120\backslash \%\backslash )$ its original length.

$($c$)$ Increasing the diameter of the needle to twice its original diameter.

$($d$)$ Reducing the diameter of the needle to half its original diameter.

$($e$)$ Increasing the pressure difference across the needle by a factor of $1\mathrm{.}5.$

$($f$)$ Reducing the pressure difference across the needle by a factor of $1\mathrm{.}5.$

$($g$)$ Reducing the viscosity of the fluid by $\backslash (20\backslash \%\backslash ).$

$($h$)$ Increasing the viscosity of the fluid by $\backslash (20\backslash \%\backslash ).$